The present invention relates to a yarn feeder for a jacquard knitting machine, and more particularly to a yarn tension bracket for use in a yarn feeder in a jacquard knitting machine which is durable in use and, has auxiliary yarn guide means that prevent yarns from being tangled.
FIG. 1 shows a yarn feeder for a jacquard knitting machine according to the prior art. FIGS. 2 and 3 show another structure of yarn feeder according to U.S. Pat. No. 5,388,747. These yarn feeders are not satisfactory in function. One drawback of these yarn feeders is that the pivot hole at the casing of each yarn tension bracket to which a respective yarn tension rod is pivotably connected wears quickly with use, casing the respective yarn tension rod to vibrate during yarn feeding operation. Another drawback of these yarn feeders is that the yarns which come out of the left thread eyes at the locating plate and then pass through the yarn guide wheels and the right thread eyes at the locating plate tend to be tangled. Because the left thread eyes and the right thread eyes are respectively horizontally aligned, each two yarns which are delivered through one left thread eye and one right thread eye at same elevation will rub against each other during feeding.
The present invention has been accomplished to provide a yarn feeder for a jacquard knitting machine which eliminates the aforesaid drawbacks. According to one aspect of the present invention, each yarn tension bracket which guides two yarns to upper and lower thread grooves at a respective yarn guide wheel comprises a casing covered with a cover plate, a pivot shaft supported on bearings between the casing and the cover plate, and a yarn tension rocker formed of two wire rods respectively fastened to two opposite round pins at two opposite ends of the pivot shaft outside the casing and the cover plate and turned with the pivot shaft, by means of the control of an adjustment screw, to adjust the tension of yarns passing through upper and lower thread eyes at the wire rods. According to another aspect of the present invention, an auxiliary yarn guide which comprises an upper thread eye and a lower thread eye is fastened to the casing and the cover plate to guide two yarns passing through the upper and lower thread eyes at the yarn tension rocker and to prevent the yarns from being tangled. According to still another aspect of the present invention, the auxiliary yarn guide comprises a U-clamp that can conveniently be fastened to the casing and cover plate.